Why Did the CDC Remove MMR Vaccine Reaction Stats from Their Consent Forms?

The Centers for Disease Control and Prevention removed several statistics on vaccine side effects from their MMR Vaccine Information Statement (VIS) this month. Federal law instructs all doctors to make sure every patient reads a VIS prior to giving consent for every vaccine. These forms are intended to give a summary of the risks and benefits of each vaccine so that patients can give informed consent, as with any other type of invasive medical procedure. Because each of the 70 doses on the childhood CDC vaccine schedule contains risk, patients are supposed to be informed of those risks before every dose.

Prior to February 12, 2018, the MMR VIS included the following moderate risks:

Seizure (jerking or staring) caused by fever (about 1 out of 3000 doses)

Temporary pain and stiffness in the joints, mostly in teenage or adult women (up to 1 out of 4)

Temporary low platelet count, which can cause a bleeding disorder (about 1 out of 30,000 doses)

The updated VIS still lists these possible side effects, but no longer discloses the numbers. They also removed the 1 in 1250 statistic on seizure risk from the combined MMR/Chickenpox VIS. The important question is why? VIS forms are intended to give information. Isn’t more accurate information better? When patients read about risks, don’t they want to know the likelihood that such reactions will happen to them as individuals? Isn’t it important to find out how frequently these adverse events occur?

There are three possible reasons these details would be removed:

Providing any type of statistical risk may scare more parents away from vaccines. Knowing there is a 1 in 3000 risk of a seizure may turn more away from the vaccine compared to simply being told such risks are “extremely small.”

New research has found that these numbers are no longer accurate. Surely if the risks were found to be lower, then a safer MMR vaccine would certainly be encouraging to patients, and the new and safer numbers would be provided, such as a seizure risk of only 1 in 4000, or 1 in 5000. Did new research find the risk to be even higher, and the CDC is unwilling to print a risk of 1 in 2000, or 1 in 1000?

The CDC now recommends that all adults who live in or near a mumps outbreak should receive a third dose of MMR vaccine. The old VIS warned that the arthritis risk to women is 1 in 4, and the more-detailed Package Insert warns that some of these women will develop life-long Rheumatoid Arthritis from this vaccine. Is the CDC worried that full disclosure would worry some women? But don’t all women deserve to know that the risk of this is quite high before they consent to an extra dose, especially if they already have arthritis? Shouldn’t they be able to choose between the unlikely risk of mumps exposure and the not-so-unlikely risk of RA?

When dealing with the health and well-being of your children or yourself, transparency in medicine is critical. Removing vital statistics from information sheets also removes informed consent in medicine which should be given to every citizen. By eliminating real adverse reaction numbers it makes side effects seem more theoretical in nature. It takes the reality out of the risk.